Those aren't really "shadows".
Those are generic wandering enemy sprites. I made them look like silhouettes so it's easy to reuse them for various enemies of the same type (e.g. all bird-like enemies would be represented by that black falcon sprite).
I never really thought of ICO when making them. Actually, I played it for the first time AFTER I finished them. Yeah, they do bear resemblance, but I've seen this design in dozens of games before (e.g. Planescape: Torment).

the game looks kinda cool. It would be nice if the shadow creatures had some sort of lag effect on them, kinda like ico or finites shadow panther on this forum. But I suppose this would be better convayed in the animation. jus a thought, nice tho.

Nice work. My only crit is that I don't think it would be physically possible to view the horizon in that projection type and that there would be no foreshortening so the small mountains and trees in the background would be the same size as they would be if they were right next to the characters. Although I've seen this kind of rule bending done in games like Goldun Sun, it still irks me.

Love the simplicity of it and the forest distancing. Is the enemy some kind of shadow army? Haha, I'll have to find a different plot for my RPG now , actually had the same kind of general shadow type of thing going. Great job on the cool mockup!